POWER TOOL TECH

By
Updated: September 6, 2012

Increasingly advanced technology has seen smart phones, smart cars, smart whitegoods and smart power tools as manufacturers research and develop faster, tougher, more efficient and more powerful products.

For cordless tools – which now account for over 50 per cent of the Australian power tool market and will be the focus of this article –  it is the battery, motor and switch which are seeing the greatest technological developments.

In WTW Issue 10 (June/July 2011) we took a look at one of the most popular tools in the market, the cordless impact driver. We put seven brands to the 75mm batten screw into 58mm LVL Tradie Tough Test and compared them for screws down, speed, runtime and other features. Results were impressive from all involved. Note, while this test gave a good indication of the speed, power and performance of products off the shelf, it did not test the long-term performance of the tools.

One year on and many brands have stated big improvements in their cordless power tools, citing longer runtime and increased power with new battery and motor technology as well as better management of the tool through microprocessors.

WTW talked to all the big players to find out the latest info on power tool technology, where the big developments are being made and what it all means for the end user.

Brush and Brushless:

Brushless is a big buzzword in power tools in 2012. Many manufacturers are stating more efficiency, service life, power and pretty much everything else one wants from their tools.

While most tradies WTW talked to knew a brushless motor does not require motor servicing and brush replacement, most were unaware of the other benefits brushless offers. Understanding these benefits first requires understanding the motor.

Hitachi Brush Vs Brushless

The best description of a brushless motor came from Panasonic Marketing Manager, Charlie Elkhoury. He said, “A brush motor is an armature with two brushes {or four – think two and four pole motors}  and they are driving a current through to give you a positive and negative. A brushless motor is a straight computer board… Brushless is digital, brush is analogue.”

Charlie said comparing a brush and brushless motor was like comparing a distributor cap in a carby engine with an electronic fuel injected (EFI) engine. He said the result was better performance.

Hitachi Power Tools released their range of brushless motors at the end of 2011 and state they are 30 per cent more efficient  than their brush predecessors, without the friction and sparking caused by brushes. They say this efficiency translates to more power from smaller, lighter and  longer lasting motors. Certainly when WTW compared Hitachi’s new range of brushless models with their older brush models, their statements of greater power and efficiency rang true. (QR CODE2)

Hitachi powertool product manager Richard Steel said as well as the increased efficiency and weight, running the motor using digital power rather than analogue power through a mechanical brush motor enables a digital switch to be used in the tool which provides more intelligent use of the  battery’s power (more on that later).

comparing a brush and brushless motor is like comparing a distributor cap in a carby engine with electronic fuel injected (EFI) engine

A Brushless motor is digitally powered, comparable to an EFI

While the industry consensus is that brushless motors have less motor wear, less friction and resistance and therefore more runtime, there are other factors contributing to the performance of a tool. In fact the Milwaukee “brush” impact driver was the fastest and most powerful impact driver tested in 2011. However the test of time is critical and manufacturers say brushless enables performance to be sustained over a longer lifespan. Milwaukee are implementing brushless motors in their new FUEL range being released around July 2012.

Of course, the other factor one must weigh up in their purchase decision is price and whether the benefits of brushless motors are required by the user.

Whatever your opinion on the type of motor in your tool, technology is fast evolving with serious competition between brands. Ultimately this competition sees increased research and development by manufacturers while also keeping prices in check, a win-win for the tradie.

Lithium ion powered

The best motor in the world means little unless you have the juice to power it. Enter lithium ion. Lithium ion came into the Australian trade market in 2005/06 quickly replacing nickel metal hydride (NiMH) and nickel cadmium (NiCD) batteries.

Lithium ion has many benefits including being smaller and lighter for the same power, having no memory effect (charging a half used battery will not reduce its capacity – as with NiCD), significantly less self-discharge when not in use and fairly consistent voltage from full charge to empty.

A Milwaukee battery unpacked

If you treat it well, lithium ion is a tradie’s best friend. Treat it badly and at best it will die. At worst it will blow up in your face… literally. If lithium ion gets too hot or is overcharged, it explodes.

Bosch Blue brand manager, Richard Fallon told WTW the main issues causing damage to lithium ion are deep discharge, over-heating and overloading.

“Deep discharge is when the voltage drops below the required minimum of the battery,” Richard said.

“The effect of that is the reduction of the lifetime of the battery and you start losing capacity to charge. So you may only get to 90 per cent then 80 per cent and the battery dies away.”

If you treat it well, lithium ion is a tradie’s best friend. Treat it badly and at best it will die. At worst it will blow up in your face… literally

Richard also said overheating and overloading {drawing too much current} by working a tool too hard or using a tool in a fashion it was not designed for can also cause irreversible damage to lithium ion, not to mention the motor.

To prevent this damage from occurring and to increase efficiency, manufacturers are placing communication systems in their tools to protect their batteries and motors from misuse as well as to effectively use every ounce of battery power.

The Brains

Bosch call it ECP (Electronic Cell Protection) and EMP (Electronic Motor Protection), Hitachi call it Multiple Protection Circuit (MPC), DeWALT have just released SAM (Switch and Module), Milwaukee are releasing FUEL and Makita have their range called STAR coming soon. All are marketing terms for their tool-battery-charger communication and management systems and these systems may vary in their exact protective functions. Other brands have communications in place however have not aggressively marketed the presence in their tools.

Bosch EMP - Electronic Motor Protection

One of the key features of the above named systems is overload protection which shuts your tool down to protect the motor and battery  if the current draw exceeds specifications.

overload protection which shuts your tool down to protect the motor and battery  if the current draw exceeds specifications

Another feature is in brushless motors allowing a digital switch and so better control over power inputted to the motor from the battery.

A number of brands have – like Bosch – had these advanced communications and protection systems in a range of their tools for many years. Festool, Hitachi and Panasonic are other examples of early pioneers.

The National Training Manager of the revered German-made Festool brand, Bruce McKinley described the monitoring as critical in the management of lithium ion and said Festool has had advanced communications systems since 2008.

“The software works out through this constant feedback exactly what the motor is doing and what load it is under. It is only going to give you what you need, so the batteries last a lot longer,” he said.

Milwaukee’s marketing manager, Marcus Monch made similar comments about FUEL.

“You can have the best {battery} cells in the world but if you don’t have the electronics then it’s not going to talk to the tool and it’s not going to know how much {current} it needs to draw,” he said.

Marcus said Milwaukee’s management system in their FUEL range even knows what tool is connected to the battery enabling better power management.

“It’ll actually regulate the amount of power it sends through to the tool by recognising it has gone onto that tool,” he said.

Richard from Bosch said their tools have a similar system.

“Bosch ECP recognises battery capacity and optimises the  performance of the tool and battery.”

If your tool keeps jamming or electronic protection is shutting off the machine, stop using it for that application and get a bigger one

While this technology is not in all brands yet, Richard said all lithium ion systems will have some sort of communications system built in with the purpose of increasing efficiency and protecting battery cells, however the degree of how much protection varies between manufacturer.

“Some put it into the tool and battery, others will put it into the battery and the charger, others will just put it into the tool. You will find that generally the DIY products are just the tool or just the battery… Bosch have it right across the board,” Richard said.

Individual cell monitoring

A lithium ion power tool battery is made of rechargeable cells similar in size to your everyday double A battery.  These are connected depending on the tool’s voltage. An 18v 3.0 amp hour battery usually consists of eight cells connected in parallel plus series to create 18v. New 4.0 amp hour batteries being released run the same connection with higher amperage cells.

Individual Cell Monitoring (ICM) is one element of the communication package that enables better use of the battery’s power and increased service life.

Charlie from Panasonic said ICM enables the tool to achieve equal power draw across all cells.

“The cell sensor computer regulates power coming into and power going out of every cell,” he said.

He added if one cell began to fail, the entire battery shuts down, protecting the battery as a whole.

Richard from Hitachi described ICM – which is part of Hitachi’s Multiple Protection Circuit (MPC) monitoring system as ”A  much more thorough version of protection.”

Individual cell monitoring has a few different names across the brands and it is a feature all brands are working to implement in their battery technology if they have not already.

Battery Pack Construction

Metabo battery pack with individual cell monitoring

The construction of battery packs is also critical in ensuring long lifespan through resilience to impacts and allowing airflow for cooling. Battery cells are usually made by companies such as Samsung, Sanyo, Sony, Panasonic and others, with cell technology and models often shared between power tool brands. Battery packs however are an individual product of the brand. All are manufactured to withstand some impact, some better than others

A battery fuel gauge is another increasingly popular feature in battery pack construction and one that is likely to be seen across more brands in the near future.

Marcus from Milwaukee said it was fairly simple to place a fuel gauge on a battery although it did cost a little more.

“We are probably on the higher echelon on costs for batteries but that is because we are providing a more all-round performance for the end-user,” he said.

Battery pack technology and the associated communicative and monitoring features housed within are a large research arm for power tool companies and a reason why these little puppies are so expensive to buy.

Panasonic’s Charlie Elkhoury explained it clearly when he said “more than half the cost of manufacturing a cordless drill comes down to the quality of the battery.”

Battery Charger:

With heat being so damaging to lithium ion cells and potentially dangerous for users, and the act of charging equating to pumping energy and thus heat into a battery pack, a charger that monitors battery conditions is important.

Most chargers such as the Rapid Optimum Charger from Makita communicate with their batteries to ensure they are not overheating. Makita product co-ordinator, Damien Taylor said Makita’s lithium-ion Rapid Optimum Charger comes with a built-in computer chip that maximises battery life.

“A micro-processor selects the optimal charging method according to the battery’s voltage, current, and temperature,” Damien said.

He added the Rapid Optimum Charge

Hitachi battery charger with fan to cool battery and electronics to communicate with it.

r (DC18RC) also has an internal fan and is constructed to encourage air circulation and thus cooling, enabling a 22 minute charge time (on a 3.0 amp hour battery) by increasing the current inputted into the battery without battery damage. Damien said the other Makita charger available (DC18SD)  did not have the cooling system and thus a slower charge,

Many other brands have similar technology in their chargers though have a longer charge time saying it was kinder to batteries to charge them more slowly with a lower current.

Milwaukee are one of the few brands that do not have a fan in their charger and Marketing Manager, Marcus Monch said it was not required because of the advanced communication between battery and charger.

“The electronics talk to the cells and they don’t overheat,” he said.

Power tool technology is improving at a phenomenal rate with ongoing research and development into improving tool and battery performance. Next time you fire up your cordless kit, take a moment to think about everything going on behind the scenes to help you get the job done.

Hot Tip

If your tool suddenly stops working, you have likely overloaded the battery and motor with a heavy application. Alternatively the battery has become too hot and the electronic management system has kicked in to prevent damage. Place your battery on the charger where air-cooling (if it is available) may help cool it faster. Insert a different battery on your tool and run it in the shade without load. This will circulate air over the motor and cool it down faster than leaving it sitting unused.

Be kind to your tool

There are horrific stories of guys pushing their tools to the limit. Jamming drills or wrenches in tough applications and hand winding to finish the job is one such example. Not only is this hard on gears but it is horrific on motors. The more advanced communications systems will shut down the tool to prevent damage, however if your tool does not have a protection system and you continue to power a stalled motor, burnout is not far away. If your tool keeps jamming or electronic protection is shutting off the machine, stop using it for that application and get a bigger one!

Words / Tom Haynes

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